Supplement Of Tryptophan Ameliorates Methotrexate-induced Intestinal Injury In Rats

The present study was conducted to evaluate the effect of tryptophan (Trp) onmorphological structure of intestinal tract, antioxidant capacity and metabolism ofSprague-Dawley rats by methotrexate-induced. The levels of serum biochemicals,different parameters of oxidative stress, heme oxygenase-1(HO-1), metabolites inrats supplemented with Trp were analyzed to discuss the possible protective effect ofTrp on intestinal injury.Methods: Male Sprague–Dawley rats (200~220g) were acclimatized for1week before the initiation of the experimentation. Rats were randomly divided intosix groups of8rats in each: normal control group (NC group), TRP control group(TRP group), methotrexate group (MTX group), low-dose tryptophan withmethotrexate group (L-TRP+MTX), middle-dose tryptophan with methotrexategroup (M-TRP+MTX) and high-dose tryptophan group with methotrexate(H-TRP+MTX). MTX was injected intravenously at a single dose (10mg/kg.bw) atday4once daily for two consecutive days. Trp was administered at three differentdoses (100,200and300mg/kg.bw) for7days in three study groups before and afterMTX injection. Saline was injected intravenously instead of MTX in the NC groupand TRP group, and distilled water was given instead of Trp in the NC group.Results:(1) Tryptophan could improve morphological structure of intestinaltract. Meanwhile the effect of low and middle dose tryptophan were more significant(P<0.05).(2) Tryptophan could decrease the level of serum D-lactic acid (P<0.05)(3) Oxidative stress could lead to imbalance of redox state in intestinal tissues, as areault, the levels of MDA and MPO increased significantly (P<0.01). Supplement oftryptophan was helpful to improve its antioxidant capacity, the effect of low andmiddle dose tryptophan were more significant in improving the antioxidant effect(P<0.05).(4) By supplement of tryptophan could enhance the HO-1expression inintestinal tissues, the effect of low and middle dose tryptophan were better (P<0.05).(5) Oxidative stress could lead to metabolic disorders in rats, Tryptophan could dropthe levels of glucose and proline while rise the levels of succinate and citrate in rats (P<0.05).Conclusion: The results indicated that supplement of tryptophan involvedreparation of structure of intestinal tract, raise of antioxidant capacity and regulationof metabolism in model rats. Tryptophan could effectively protect tissues againstoxidative injury, which may be related to the expression of HO-1.